Stone transport
The stone transport has a long tradition and is still a dangerous and hard work. With the development of the machines, the transport task was made considerably easier. The development of the means and methods of transport for natural stone was and is dependent on the construction tasks and the development of the means of production .
Man and machine
Initially, rough stones that could be transported by humans were transported by hand or with wooden rollers and, after the invention of the wheel, with wooden wheelbarrows . A special form of stone transport was the so-called lizzatura practiced in Italy, in which the raw blocks were transported to the valley over an inclined plane attached to a rope. This method is said to have been used in ancient Greece and Italy. The blocks were then loaded onto ox carts and transported further. Before machines powered by steam, gasoline or electricity were invented, moving natural stone was a human effort, often with the help of winches. The obelisk from Nero's circus was erected in 1585 by order of Pope Sixtus V by 900 workers, 90 horses and with the help of 48 winches .
With the invention of machines at the end of the 19th century, in addition to the marble railway, there were also cable cars in Carrara to transport Carrara marble from the mountains. The route of the marble railway, especially the bridge structures, has been preserved to this day, the cable car is not.
In Laas today (2008) there is next to the so-called Lasa marble railway, a cable winch connected to the mountain, with which rough blocks of Lasa marble are transported down to the valley via an inclined elevator.
Today there are no major technical problems to transport ingots weighing up to 200 to 300 tons.
Today's stone transport
In today's stone transport, a distinction is made between slings and load handling devices in the technical sense with regard to the fastening of the raw blocks.
Block, tranche and plate transport
Blocks are usually up to 3.60 meters long, up to 1.60 meters deep and rarely up to 2.00 meters high. The size of the rough blocks depends on the rock occurrence, on the thickness of the layer or bank, as geologists say, and on the subsequent use or the cutting depth and length of the stone saws . Stone masons refer to slabs that are thicker than 80 millimeters. This stone thickness is referred to as slabs that are too large and have rough, unsawed edges. Nowadays natural stones are traded globally. After the raw blocks have been extracted in the respective quarry, they can be loaded or shipped using modern transport equipment. In the national ports, the raw blocks are unloaded with the existing crane systems in the port and transported to the processing plants by truck.
Stone transport in the quarry with wheel loaders
Ship unloading with cranes
Onward transport after crane unloading with forklifts in the port
Transport by truck to the processing plants
Once the stone blocks have arrived at the processing company, they are unloaded either with forklifts or gantry cranes . In most cases, gantry cranes are used in the stone industry because they require the least amount of space. The blocks made of natural stone are hung in steel cables and stacked. Before further processing, the raw blocks are placed in so-called block turner, if necessary. This is necessary because natural stones have a storage that shows different textures (arrangements) of the minerals depending on the cutting direction. Furthermore, natural stones that are installed outdoors are sawn open for durability and technical reasons with the natural bearing as the blocks are embedded in their rock layer.
Gantry crane transporting stones in processing plants
Block turners are used for further processing depending on the texture of the sawed surfaces
Block division with a wire saw on a mobile saw table on rails
Raw panel transport with stone shears that grip the panel at the top
Stone scissors
Stone shears are mainly used for stone transport for so-called non-size slabs with cranes or forklifts . Unmeasured slabs are unformatted slabs, polished on one side, with a length of more than 3.00 meters, a height of more than 1.50 meters and a thickness of 2 to 8 centimeters. So that the polished plates are not scratched by the scissors and have a secure adhesion in the scissors, their contact surfaces are rubberized.
Vacuum lifter
Vacuum lifters are used in many stonemasons because they can be used to lift both smooth and rough stone surfaces with suction lips specially made for the stone industry, without the risk of flaking. The suction lifter creates a vacuum between the suction lifter and the surface of the natural stone to be transported. In addition to these individual mobile suction cups, there are specially made suction cup devices that can be attached to forklifts in order to transport non-dimensional panels that are at risk of breakage when transported flat. In addition, stationary suction lifters at the end of the sanding line are used to automatically remove the stone slabs from the production line.
Occupational safety
The trade association rules must be observed with regard to work safety when transporting stones. This includes, above all, the protection and storage of the means of transport, observance of the load capacity and the weight to be transported and, when using suction lifters, the ongoing checking of the tightness. In addition, the means of transport, lifting equipment (crane, forklift) and the means of support (C-shaped transport hook and safety lock, forklift fork, etc.) must be checked at certain times in accordance with the applicable rules.
Historical stone transport
Ox cart
Most of the stone transport was carried out with so-called ox carts. They were sturdy wooden carts that were pulled by teams of oxen. The ox carts were initially one-axle and later two-axle.
Lizzatura
The lizzatura (Italian: Lizza is a sledge ) is an ancient method of transporting raw blocks from the quarries. It is believed that this method of transport was already used in ancient Greece and by the ancient Romans in Carrara to transport rough blocks.
The sledge in Carrara consisted of two six to 12 meter long beech trunks on which the load ( Carica ) was attached. Individual blocks of Carrara marble weighing up to 25 tons could be loaded onto the sledge. The cargo was previously secured with hemp ropes and from 1920 in Carrara with steel ropes. The three transport ropes were wrapped around wooden posts set in stone and the slack of the rope slowly moved the sledge down to the valley. The sledge slid on smaller soaped pieces of wood called parati . Foreman, who was in front of the sledge, directed the group of workers, the Lizzatori , who had the most dangerous jobs. Up to fourteen workers were required for transportation. The last professional lizza was carried out in Carrara in the 1960s; Once a year, Lizzatori hold a lizzatura in the small town of Miseglia to maintain tradition.
Ropes and chains
Ropes and chains are among the lifting accessories . Ropes used to be made from hemp. Today they are made of plastic. In the case of ropes, there are so-called endless ropes, which are called straps in practice. Since the panels produced by stone saws sometimes have razor-sharp edges, so-called edge protectors are attached to the plastic ropes, which prevent them from being dragged through or cut through.
The chains have links made of ferrous metals.
Ropes and groove
Natural stones that had been hewn could be attached to ropes when they were being transported above head height . For this purpose, U-shaped grooves had to be driven in on both ends of the stone , which were deep and wide enough to accommodate ropes. The ropes or an endless rope could be caught with a hook and transported in this way. This form of transport was already used with success in ancient Greece and Rome . They are no longer used today.
Ropes and bosses
The transport takes place by means of fastenings at three points. A recess was worked into the stone on one side and a boss was left on the other two sides . The bosses prevent the stone to be transported from being able to move sideways. The bosses are knocked off after they have been moved so that further stones can be connected tightly.
Chains
When transporting rough stones, iron chains are used for transport, as ropes can be worn through on the rough edges.
Stone scissors
The stone shears are among the load handling devices .
Historic stone scissors
Stone scissors, also known as stone tongs, called devil's claw , were used in the Middle Ages to transport stones with ropes on cranes . The functional principle of the historical stone scissors can be seen from the sketch. The scissors grip two holes made before the transport and when the stone is lifted, the stone scissors become force-locked.
The transport holes on the outside of the walls can be seen in many historical buildings. Since many of the historical buildings that are now stone-exposed were originally plastered, the transport holes were not a visual problem at the time of construction. Today (2008) many historical stone buildings have become visible as stone and the transport holes are visible.
Stone scissors in the 19th century
A more modern form of stone scissors is shown in the adjacent drawing. It was used from around the 19th century. For this purpose, dovetail-shaped holes were punched in the natural stone, then the scissors were inserted and locked with a pin (C). The transport holes were hammered into the bed joint and were not visible on the outside.
wolf
A load handling device for ashlar that has been in use for centuries is the so-called wolf . A double-sided dovetail-shaped hole was knocked into the stone to be transported, then shims, called fitting pieces, and the metal plate, the so-called clamp with transport ring, inserted. The wolf hole had to be struck exactly and after the wolf had been inserted, remaining cavities had to be closed with finely sieved sand. When the stone was lifted, the wolf spread itself in the stone. A distinction is made between the big and the small wolf and it was possible with these devices to lift loads of up to 2 tons.
The little wolf was available with two fitting pieces or with just one cock . The ring only led to the transport through the dovetail-shaped cock (the big wolf had a straight cock). Clamps and fitting pieces were enclosed by a locking clasp below the transport ring. The depth of the wolf hole was about 7 cm.
The large Wolf has, as shown here, two antisymmetrically formed Beilagsplatten and is fixed on the insert with the bolt and bracket. The depth of the wolf hole when using the big wolf was about 12 to 15 cm.
Nowadays (2008) the wolf is only rarely used because heavy-duty anchors have displaced it. When using dowels, impact drills can be used, which minimize the time required. The breakout load at the dowel hole must be determined when using a wolf or dowel.
See also
literature
- Gustav U. Breymann (first), Heinrich Lang (edit.): General building construction theory with special reference to building construction. A handbook for lectures and self-study (Die Konstruktionen in Stein; Vol. 3). Edition "Libri Rari" Schäfer, Hanover 1981, ISBN 3-88746-013-8 (unchanged reprint of the 7th combined and extended edition of Gebhardt, Leipzig 1903).
- Luciana and Tiziano Mannoni: Marble, Material and Culture , Callwey, Munich 1980, ISBN 3-766-70505-9 .
- Work safety rules . (PDF file; 236 kB)
- STEINMETZHANDWERK AND SACRAL ARCHITECTURE Inaugural dissertation, University of Münster (PDF file 2560 kB)